Sonar transducers



Jan. 14, 1958 '.1. PZONEILL 2,820,2M

soNAR TRANsDUcERs- Filed May 28, 1949 f2 sheets4sheet 1 ATTORNEY Jan.14, 1958 P @NEILL l Zgl soNAR TRANsDUcERs Filed May 28', 1949 2Sheets-Sheet 2 ATTORNEY United States Patent SONARTRANSDUCERS John P.GNell, Chestnut Hill, Pa., assignor, .by mesne assignments, .to 'the'United States of America as represented by the Secretary of the NavyApplication May 2S, :1949, Serial No. 96,106

s Claims. (cran-s) This invention relates to underwater signaling andmore particularly to an improved method of,and fapparatusfor,ydetermining the directional characteristics of `a "compressional wavetransducer.

Underwater `sound ranging systems generally use acom- ,pressional wavetransducer, lsuch zas a magnetostrictive or piezo-electric device. invone Asys-tem, the transducer transmits sound waves through Iwater andthe energy readected `from an object is received and used to determine`the direction and distance of the object. In another system, or evenYcombined with the above system, the

transducer is merely used as a receiving device to Vpick up theunderwater sounds made by other ships whose approximate location is thenobtained by a form of triangulation.

,In order to obtain a wider angle, 'or an omni-directional searchpattern, it had been customary `to :rotate ra :single transducer havinga single frontal :lobe pattern. This was replaced -by a number oftransducers 'facing in di'ierent directions and finally by what is:known as a -Lscannirrg compressional wave transducer made up of manyelements arranged to form a ligure of revolution such as a cylinder. Bycontrolling the electrical phasing of the elements the scanning searchpatterns can 4be made as wide or as narrow as desired.

Thesetransducers'are generally attached to the bottom of ships. It wasfound that, when a number of ships travelled inconvoy and `would attemptto use their v.sound ranging systems, there would be interference pickedup from each other which was diflicultto eliminate electrically due toits continuously shifting nature caused by the shifting of the shipspositions. Furthermore, if the .complex electrical phasing system'developed defects, the 'sound ranging system was yrenderedsubstantially ineiiective to determine the direction of other ships orsubmarines.

lt is therefore an object of this invention to provide improvedapparatus to control the directional pattern of an underwater'compressional wave transducer external to said transducer.

It is a further object of this invention to provide improved apparatusto control the directional pattern of an underwater scanning transducer,which apparatus is simple in construction.

It is still a further object of this invention to provide improvedapparatus to control the directional pattern of an underwater scanningtransducer, which apparatus is exible and simple to operate.

n It is also an object of this invention to provide irnproved apparatusto shield an underwater scanning transducer from undesired signals. Onesolution for these prior art diiculties is to provide a supplementarydirectional control system which is simple to operate and reliable, andwhich introduces no further complexities into the transducerconstruction and operation.

These and other objects are therefore achieved in accordance with thisinvention by spacing around the scanping transducer adjustable balesections which are coated Fice with a compressional wave `ratteiniaturgsubstance. These bathe sections are individually adjustable between openand close positions thus permitting fa determination of both adirectional pattern for 'the `transducer as Well as fthe portion of thetransducer to be shielded from vundesired signals.. i

The novel features of my invention, -both `as to lts 'organization .andmethod .of operation, as well `as additional objects and advantagesthereof, best be under stood from the :following description, o t anembodiment thereof when read in connection with the accompanyingvdrawings wherein reference characters are applied to parts havingsimilar function and wherein,

Figure 1 is a lView of 1a ship lsnowing v'the relative loca @tion 4'of ascanning Vtransducer under said ship,

Figure 2 is a `plan view fof my invention, partially `in section,

Figure 3 is a sectional view of my invention taken along the lines 3 3of Figure `2,

Figure -4 is a View in detail y'of the gear y'apparatus :for controllingthe effectiveness of a section of the directional bathe,

Figure 5 is a View of .a system for rotating the gear apparatus ofFigure 4 4and .simultaneously indicating the position of the staves vofthe `:baille section.

'Referring to Figure l, there is shown la scanning transfducer 10fastened to the bottom .of a ship 12. Surrounding the scanningtransducer is La streamlined thin steel :dome 14 which is used for thepurpose of eliminating friction drag on the ,ship as well asvinterfering noise which would be :creat-ed in thetransducer if it were.perm'itted to drag through the water.

1n Figure .2 'of the y'drawings there vmay lbe seen 'sever-a1 :bafflesections 16 of .my inventionopposing the active area of the transducer.yEach 'badie section 16 consists of a number of staves which:arepivotally mounted at .either iend, by lmeans of pivot rods Ztl, inoffset portions of vthe bale frame 22. The pivot rod :at the upper end:of each stave 18 extends through the bafe frame offset yand :hasattached :thereto a stave :gear 24. A rack gear 26 ,is associated witheach Abaffle section 16 and simultaneously meshes with all the stavegears 24 in the bade section. .Each rack gear 26 is driven by a piniongear 2'8 which is driven through a gear speed Vreduction box .30 `by '-amotor 3'2.

Figure 3 :of the drawings represents a `view of .the Itransducer andbafe sections taken along the section 3--3 in Figure .2. This v-iewshows :the bathe :sections 16 in :a hexagonal array around thetransducer. The staves I8 of the lower bale ysection 16 are shown in .anopen position and the staves .18 ofthe remaining vbaille sections 16 areshown in a closed position. As shown, the transducer 10 will have amaximum directivity in the direction of the open bafe section, the otherclosed baffle sections simultaneously serving as a screen tosubstantially repress or block any radiation from the transducer and asa shield to protect the transducer from disturbances originating fromthe directions of the colsed bafe sections.

Thus, by driving the proper pinion gears 28 to operate the proper bafesections 16, the scanning transducer 10 may easily be made directionalin one or more of the directions of the six baie sections 16 andlikewise, may be shielded from noise from the direction of one or moreof the six bafe sections 16. Baie sections 16 may be arranged about thetransducer to form a polygon, having as many sides as desired, toachieve given radiation patterns or shielding.

Partially opening a bale section 16 reduces the sensitivity andradiation through the staves 18 of that battle section.

Referring to Figure 4 of the drawings there may be seen the rack gear 26and pinion drive 28 on the stave gears 24 of an open baille section 16.The appearance of the staves 18 when the baille section 16 is closed isshown by the dotted staves. As may be seenfrom the closed position, thestaves are placed adjacent to one another at a distance slightly lessthan the width of the individual stave. This is done so that, when thebaille section is in the closed position, the staves will overlap eachother and a positive closure is thus eiectuated. A stop pin 27 extendsthrough a suitably dimensioned limiting slot 29 in the rack gear 26 andlimits the rack gear travel so that there is no overdrive on the staves18. The limit of the open and of the close positions of each baillesection is thus positively ilxed.

Figure shows a system for controlling the amount of baille areapresented to the transducer, or the stave angle, while simultaneouslyindicating this on a meter. By turning the knob 34 which is attached bya shaft 36 to the rotor of a servo motor 38 a second servo motor 40electrically coupled thereto is proportionately displaced. The rotor ofthe second servo 40 is coupled by any desired mechanical means to thepinion gear 28 associated with a baille section 16 and the section isaccordingly opened or closed.

A gear 42 on a shaft 36 meshes with a second gear 44 which is used tooperate a meter 46. The dial of the meter 46 is calibrated, as desired,between the open and close positions. This indicating system is shownmerely by way of example. Any other well known method for indicating thecondition of the baille may be used. One such method is electricallycoupling a properly calibrated meter to the servomotors, the meter beingphased to be porportionately displaced with the servos.

It has been found that if the staves are made or coated with a substancewhich has numerous air spaces therein, such as a mixture of cork andneoprene, the attenuation as well as the absorption without reflectionof underwater compressional waves is substantially complete. It istherefore also within the scope of my invention that the staves eitherbe made from, or coated with, a compressional wave absorbing andattenuating material. Thus, both the reilections from the closed baillesections 16 back to the transducer as well as transmission of noisethrough the closed baille sections 16 to the transducer 10 aresubstantially reduced.

From the foregoing description it will be readily ap parent that I haveprovided a simple and reliable mechanical baille to determine thedirectionality of a scanning transducer, as well as to provide shieldingtherefor. The baille is utilizable by itself or in conjunction with theelectrical phasing means previously mentioned to render a scanningtransducer sharply directional, without complicating either thetransducer structure or use.

The transducer need not be totally enclosed by the sol baille sections,but only a few baille sections may be used and positioned or movedaround the transducer to shield a required area. When traveling inconvoy, or close to a shoreline, or any other source from whenceinterfering noise may emanate, the baille is used to substantialyeliminate those noises and thereby prevent masking of sound from desireddirections. Although I have shown and described but a single embodimentof my present invention, it should be apparent that many changes may bemade in the particular embodiment herein disclosed, and that many otherembodiments are possible, all within the spirit and scope of myinvention. For example, the transducer need not be totally enclosed bythe baille sections, but only a few baille sections may be used andpositioned or moved around the transducer to shield a desired areathereof. Therefore I desire that the foregoing description shall betaken as illustrative and not as limiting.

What is claimed:

1. The combination with a scanning compressional Wave transducer havinga cylindrical active area of a polygonal baille surrounding saidcylindrical active area, said baille comprising a plurality of pivotallymounted staves, a stave gear coaxially mounted at one end of each stave,a rack gear for each side of said polygonal baille simultaneouslyengaging the stave gears in the associated side, and pinion gearsrespectively engaging each of said rack gears whreby the directionalpattern of said transducer is determined by the setting given to eachpinion gear.

2. The invention recited in claim 1 wherein said polygonal baille ishexagonal and said staves are coated with a mixture of cork andneoprene.

3. The invention recited in claim 1 wherein there is provided, inaddition, means to drive each of said pinion gears, and means coupled toeach of said pinion gears to indicate the angular positions of theassociated staves.

References Cited in the ille of this patent UNITED STATES PATENTS1,348,826 Fessenden Aug. 3, 1920 1,394,482 Fessenden Oct. 18, 19211,397,949 Fessenden Nov. 22, 1921 1,705,243 Dunham Mar. 12, 19291,825,465 MacDonald Sept. 29, 1931 2,078,302 Wolif Apr. 27, 19372,114,680 Goldsmith u Apr. 19, 1938 2,430,568 Hershberger Nov. 1l, 19472,527,222 Iams Oct. 24, 1950 FOREIGN PATENTS 5,183 Australia June 27,1932 of 1931 395,081 Great Britain July 13, 1933

